@Wyald There is someone behind that incompetent noble. It was mentioned he should have been punished already, but nothing happened, because someone is delaying it.
I think it was actually planned and he just used that guy. He doesn't care if the noble guy dies or not. So I think he wants either the girl dead or after the boy, which is why the weapon just 'happened' to be compatible.
Getting rid or hiding the weapon seems unlikely, since people have been down to floor 30 already. Well or just short term and to retrieve it in secret later.